Equine Gastrointestinal Tract Research Articles

147 The ‘horse-side’ of host-microbe interactions and gastrointestinal homeostasis in the equine hindgut

Abstract Homeostasis is a complex physiological process that enables biological systems to maintain balanced internal environments in response to internal and external stimuli. In the equine gastrointestinal (GI) tract, homeostasis involves a network of factors that regulate gene expression, maintain the integrity of the mucosal barrier, and modulate immune responses to pathogenic microorganisms while supporting commensal bacteria that provide benefits to the host (Figure 1). These factors work together and respond to changes in diet, environment, external stress, and challenges by infectious agents or toxins. Proper gastrointestinal function is dependent on maintaining homeostasis in the system, and the dynamic interactions between the microbial population (the microbiota) and the equine host are central to this equilibrium. The regulation and interplay between the equine host and GI microbiota are evident in the distribution of distinct microbial communities within the various compartments of the equine hindgut. The contributions of each compartment to digestive physiology and the overlap with various stages of microbial fermentation in the equine hindgut are well-researched. What remains to be documented is gene expression in tissues of the equine GI and the underlying role this might play in the processes of digestion, physiology, and homeostasis in the GI. To better understand the roles that host gene expression plays in the interactions with the microbiota, it is critical that we investigate gene expression in the different tissues along the intestinal tract. Protein-coding genes are crucial in maintaining the health of the gastrointestinal tract. They direct the synthesis of various structural elements, molecular transporters, and digestive enzymes, which support digestion, nutrient absorption, and gut integrity. Non-coding genes also play an important role in regulating protein-coding gene expression, modulating immune responses, and maintaining gut barrier function. Moreover, there is evidence that non-coding transcripts regulate the composition of microbial communities in the GI tract. The presentation will focus on the current research and future directions for investigating protein-coding and non-coding gene expression to understand the mechanisms involved in the host-microbe interaction in the equine hindgut and their potential role in maintaining GI homeostasis.

Is butyrate concentration in the equine gastrointestinal tract altered during and after surgery for treatment of large colon obstruction?

Is butyrate concentration in the equine gastrointestinal tract altered during and after surgery for treatment of large colon obstruction?

22 Evaluating the core bacterial microbiome of 1,787 horses

The core bacterial microbiome can be defined as the bacteria that are consistently prevalent within a given population. Determining the core microbiome of the equine gastrointestinal tract would allow for the development of probiotics, prebiotics, and management techniques to promote the growth of these taxa and subsequently support horse health. The Microbiome Quotient project (MQ; Purina Animal Nutrition, Gray Summit, MO) aims to determine the core bacterial microbiome from a repository of rectal swabs obtained from thousands of horses across various locations, breeds, ages, and diets, among other factors. To this end, the bacterial DNA of 2,057 rectal swabs were extracted using the Quick-DNA Fecal/Soil Microbe Miniprep kit (Zymo Research, Irvine, CA) and the V3-V4 hypervariable region of the 16S rRNA gene was sequenced by following the Illumina 16S Protocol (San Diego, CA). Data were initially filtered with DADA2 within the QIIME2 pipeline. The data were filtered again in R (4.2.2) to remove samples with missing data points as well as samples with low sequencing depth (<1,000 sequences). In total, 1,787 samples were considered for downstream analysis. The core microbiome was determined by using the Microbiome and qiime2R packages in R to aggregate taxa at the genera level across allsamples with the criteria that the taxa must exceed 0.1% relative abundance in over 70% of the samples (prevalence ≥ 0.7). The data were then analyzed within the following top 5 breeds: Quarter Horse (n = 567), Thoroughbred (n = 314), Warmblood (n = 177), Paint (n = 105), and Arabian (n = 79). The top 15 genera across all samples consisted of Rikenellaceae RC9 gut group (12.58%), uncultured genus (6.79%), Erysipelotrichaceae UCG-004 (4.80%), Ruminococcaceae UCG-002 (4.09%), Akkermansia (3.89%), Ruminococcaceae UCG-010 (3.62%), Arcanobacterium (2.84%), Phascolarctobacterium (2.33%), Streptococcus (1.90%), Treponema 2 (1.75%), Prevotellaceae UCG-001 (1.71%), Mycoplasma (1.64%), Prevotellaceae UCG-004 (1.63%), Clostridium sensu stricto 1 (1.57%), and Alloprevotella (1.56%). Three unique genera were observed between the top 5 breeds and were Campylobacter (Warmblood), Bacteroides (Arabian), and Ruminococcaceae UCG-004 (Paint). Further investigation of this growing database within and between other variables related to health (e.g., age, Body Condition Score, and history of disease) is necessary to fully characterize and understand the function of the equine gastrointestinal core microbiome and to determine the best practices for supporting gastrointestinal health.

18 Fecal microbial metabolite profiles are unaltered by laminitis history

Microbial metabolites of the equine gastrointestinal tract may confer information about health and susceptibility to disease. Laminitis is often associated with metabolic disturbances, but little is known of its impact on functional microbial metabolism. A pilot study compared metabolomic profiles of feces collected from 55 native ponies, comprising n = 15 pairs of previously laminitic (PL) and non-laminitic (NL) ponies matched for location, diet, and management, and n = 25 ponies suspected of having an active episode of laminitis (SL) but without clinical diagnosis. Targeted liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis was used. Univariate analyses (ANOVA with Fisher's least significant difference comparisons of PL, NL and SL groups) was performed with significance set at P < 0.05 following Benjamini-Hochberg correction. Principal component analysis (PCA) wasapplied to visualize clustering of individuals. Analysis was performed using the MetaboAnalyst 5.0 web-based interface. Of a panel of 167 metabolites, 104 were identified in the feces, however, none were significantly different between the laminitis status groups. Assessment of the PCA scores plot revealed no clustering of individuals by metabolic profile based on laminitis status. The similar fecal metabolite profile of previously laminitic and non-laminitic ponies indicates that laminitis may not result in significant long-term, alteration of microbial metabolism. Future work to combine these data with that of microbial abundance and species diversity in the feces may reveal further insights into the functional microbial metabolism in laminitic and healthy animals.

Gastro-Intestinal Microbiota in Equines and Its Role in Health and Disease: The Black Box Opens.

Horses are large non-ruminant herbivores and rely on microbial fermentation for energy, with more than half of their maintenance energy requirement coming from microbial fermentation occurring in their enlarged caecum and colon. To achieve that, the gastro-intestinal tract (GIT) of horses harbors a broad range of various microorganisms, differing in each GIT segment, which are essential for efficient utilization of feed, especially to use nutrients that are not or little degraded by endogenous enzymes. In addition, like in other animal species, the GIT microbiota is in permanent interplay with the host's cells and is involved in a lot of functions among which inflammation, immune homeostasis, and energy metabolism. As for other animals and humans, the horse gut microbiome is sensitive to diet, especially consumption of starch, fiber, and fat. Age, breeds, stress during competitions, transportation, and exercise may also impact the microbiome. Because of its size and its complexity, the equine GIT microbiota is prone to perturbations caused by external or internal stressors that may result in digestive diseases like gastric ulcer, diarrhea, colic, or colitis, and that are thought to be linked with systemic diseases like laminitis, equine metabolic syndrome or obesity. Thus, in this review we aim at understanding the common core microbiome -in terms of structure and function- in each segment of the GIT, as well as identifying potential microbial biomarkers of health or disease which are crucial to anticipate putative perturbations, optimize global practices and develop adapted nutritional strategies and personalized nutrition.

Morphomolecular characterization of Strongylus vulgaris isolated from donkeys with special references to histopathological study on the affected organs.

Equine gastrointestinal tract is infected with Strongylus vulgaris (S. vulgaris) which is highly pathogenic parasite for its harmful effect on cranial mesenteric artery during its migration. So, this study was applied for identification of S. vulgaris in donkeys ultramorphologically and molecularly. In addition to, detection of the pathological effect of larval stage of S. vulgaris on the mesenteric arterial system using histopathology and immunohistochemistry. During the period from September to December; 2019, 60 male and 20 female donkeys at the Giza Zoo was postmortem examined. S. vulgaris adults and larvae were collected from the large intestine and cranial mesenteric arteries (CMAs), respectively. Ultramorphological examination of the collected adults was done using scanning electron microscope (SEM). DNA was extracted from 5 larvae and 6 adults for further conventional PCR studies and sequencing of the internal transcriped spacer 2 (ITS2) gene. The ITS2 gene were amplified and showed bands at 148 base pair (bp). The ITS2 gene nucleotide sequences of all isolates were aligned using Basic Local Alignment Search Tool (BLAST). Histological sections of S. vulgaris affected mesenteric arteries exhibited the presence of the parasite larvae either in the lumen with thrombus formation or attached to the intima. Most of the detected inflammatory cell populations were CD68-positive cells. From these results, it can be concluded that the ribosomal spacers genes could be used as markers for Strongylus species identification in eggs collected from equine feces as a beneficial method of diagnosis. Also, it could be important in disease surveillance, improving preventive measures and developing an effective control strategy.

Distribution of Glp-1 Secreting L Cells in the Equine Gastrointestinal Tract

Distribution of Glp-1 Secreting L Cells in the Equine Gastrointestinal Tract

Modeling digesta retention in horses fed high or low neutral detergent fiber concentration forages

One factor influencing the extent of feed degradation is the length of time feed resides at the site of digestion. Traditionally, mean retention time (MRT) is measured for the entire equine gastrointestinal tract (GIT), but retention time in specific organs may be more relevant to understanding digestion. Multi-compartment models theoretically partition the GIT to potentially represent MRT in individual segments. The objective of this study was to apply a multi-compartment model to digesta passage in horses fed forage-based diets. We hypothesized forage neutral detergent fiber concentration would alter total tract MRT, transit time (TT), and compartment retention time. Six geldings (4 ± 1.5 y, 545.0 ± 64.5 kg, mean ± SD) were randomly assigned a diet of timothy cubes (Hi NDF, n = 3) or alfalfa cubes (Lo NDF, n = 3) fed at 1.53% BW and concentrate at 0.22% BW (DM basis). After a 15-d dietary adaptation, geldings were orally dosed with Co-EDTA and Yb-labeled NDF residue to determine liquid and particulate retention time. A total fecal collection was conducted for 120 h after marker dosing. Samples were analyzed for Co and Yb concentrations by inductively coupled plasma spectrometry. Gamma distributed age-dependent two compartment models were fit to marker excretion curves for each gelding (MATLAB, vR2014a). Diet effects were analyzed by ANOVA (SAS, v9.3). There was no effect of diet on total tract MRT (liquid 21.78 ± 0.79 h, particulate 25.80 ± 0.79 h, mean ± SEM). However, liquid TT was longer (P = 0.041) in the Hi NDF diet (7.25 ± 0.91 h) than the Lo NDF diet (3.86 ± 0.91 h), and liquid age-dependent compartment retention time was shorter (P = 0.019) in the Hi NDF diet (8.40 ± 0.84 h) compared with Lo NDF diet (11.72 ± 0.84 h). Particulate TT was longer (P = 0.029) in the Hi NDF diet (8.24 ± 0.96 h) than the Lo NDF diet (4.54 ± 0.96 h). Although there was a difference in DM digestibility (Hi NDF: 50.1 ± 2.31%; Lo NDF: 60.0 ± 2.31%; P = 0.002), covariate analysis did not show a significant relationship between MRT or compartment parameters to diet digestibility. Additional research should pursue methods to ascribe physiological meaning to mathematically determined compartments. Nonetheless, the current data indicate using a multi-compartment model can identify differences in some digesta rate parameters between high and low fiber diets that were not apparent using total tract MRT alone.

33 Profiling miRNA transcripts in the equine hindgut by quantitative PCR

Gastrointestinal (GI) homeostasis in a horse results from dynamic interactions between a horse's gut physiology and the microbes in the various compartments. MicroRNAs (miRNA), single-stranded 20–22 basepair RNA molecules involved in post-transcriptional control of gene expression, have been implicated as an essential mechanism for control of gastrointestinal physiology and communication between host and microbe. Researchers have described how host-derived miRNAs influence microbial communities' composition in the GI. We have recently described how the pelvic flexure separates distinct microbial populations in the equine hindgut and subsequently have wondered if equine miRNA transcripts expressed by GI tissues could have a role in maintaining this separation. Investigations to characterize miRNAs' expression profile and other non-coding RNAs in the equine GI tract are limited. To address this, it is critical that we first know something about the expression of non-coding transcripts in the equine GI. This study investigated miRNA expression in tissues of the hindgut surrounding the pelvic flexure. RNA was isolated from the intestinal epithelium of 3 4-year-old American Quarter Horses collected from the right and left ventral colon (VC), pelvic flexure (PF), and right and left dorsal colon (DC). The miRNA transcripts were reverse transcribed using the miScript II RT kit, and relative abundance was quantified using the miScript SYBR Green PCR kit and primer sets for 286 annotated mature equine miRNAs. Biological replicates were pooled, and differential expression was determined following normalization by the delta Ct = Ct(target) – Ct(sample) method. A total of 230 miRNA transcripts were expressed in at least one GI location, with 60 expressed in all 5 locations. Twenty-eight transcripts had expression restricted to a single site, 5 of which were only expressed in the pelvic flexure. Additionally, 42 transcripts have patterns of expression across a subset of anatomical locations. Notably, 10 transcripts were expressed in the VC and PF, 5 transcripts were expressed in the DC and PF, and 15 transcripts were expressed in the VC and DC but not PF. Pathway and target analysis for the miRNAs with compartment restricted expression was performed using DIANA TOOLS. Of note, miRNA transcripts expressed only in the PF were predicted to target genes in the Hippo signaling pathway, which is associated with the regulation of intestinal tissue proliferation and homeostasis. Further investigation of miRNA expression in the equine hindgut will improve our understanding of gastrointestinal homeostasis's regulatory processes.

70 A comparative in vitro analysis of coated and non-coated yeast survivability at simulated equine gastrointestinal pH conditions

Fermentation in the equine hindgut is key to ensure the assimilation of dietary components such as vitamins, amino acids, and minerals. Furthermore, microbial fermentation products (of volatile fatty acids) provide horses with energy. Imbalances in the gut microbiota could impact the rate of fermentation leading to physiological responses such as hindgut inflammation, over production of lactic acid and ulceration. Feed supplementation with direct fed microbials (DFMs) is a common approach to restore microbial balance and ensure animal health. DFMs transit the gastrointestinal tract through highly acidic conditions in the stomach could result in a reduction of the initial DFMs concentrations. The use of coating technologies to encapsulate pH sensitive microorganisms is a way to ensure the delivery of high concentrations of DFMs in the hindgut. The aim of this study was to evaluate the survivability of a coated and non-coated concentrated yeast at pH 2, 6.3, and 6.8, to simulate pH conditions and digesta residence times of an equine stomach (1 h), small intestine (5 h) and cecum (17 h), respectively. A total of 2 replicates of Saccharomyces cerevisiae concentrate and a coated protected lyophilized Saccharomyces cerevisiae were added to MRS (selective media) broth and RPMI broth (non-selective media) at pH2; 2 additional replicates of each product were added to each selective and non-selective media at pH 7 (control). Samples were incubated at 38°C for one hour; after incubation samples were washed and media at pH 6.3 was added. Tubes were incubated for 5 h, after incubation media at pH 6.6 was added for a final 17-h incubation. pH was measured and S. cerevisiae counts were plated for enumeration after each incubation period. One-way ANOVA was used to identify statistically significant differences among groups. Counts of the coated S. cerevisiae were between 9.8 and 10.1 log10 cfu/g in selective and 9.6–9.8 log10 cfu/g in non-selective media. These counts were not significantly (P > 0.05) reduced compared with controls in selective (10.3–10.4 log10 cfu/g) and non-selective (9.7–10.3 log10 cfu/g) media. No differences were observed between coated – and non-coated concentrated S. cerevisiae. These results showed that S. cerevisiae used in this study survived the simulated transit times and pH conditions of the equine gastrointestinal tract. Concentrations of S. cerevisiae above 9 log10 cfu/g reached cecum simulated pH conditions, the high concentrations found suggest its potential use as a DFM that could enhance dietary components assimilation in the equine hindgut.

Effect of hay type on cecal and fecal microbiome and fermentation parameters in horses.

The effect of hay type on the microbiome of the equine gastrointestinal tract is relatively unexplored. Our objective was to characterize the cecal and fecal microbiome of mature horses consuming alfalfa or Smooth Bromegrass (brome) hay. Six cecally cannulated horses were used in a split-plot design run as a crossover in two periods. The whole plot treatment was ad libitum access to brome or alfalfa hay fed over two 21-d acclimation periods with subplots of sampling location (cecum and rectum) and sampling hour. Each acclimation period was followed by a 24-h collection period where cecal and fecal samples were collected every 3 h for analysis of pH and volatile fatty acids (VFA). Fecal and cecal samples were pooled and sent to a commercial lab (MR DNA, Shallowater, TX) for the amplification of the V4 region of the 16S rRNA gene and sequenced using Illumina HiSeq. The main effects of hay on VFA, pH, and taxonomic abundances were analyzed using the MIXED procedure of SAS 9.4 with fixed effects of hay, hour, location, period, and all possible interactions and random effect of horse. Alpha and beta diversities were analyzed using the R Dame package. Horses fed alfalfa had greater fecal than cecal pH (P ≤ 0.05), whereas horses fed brome had greater cecal than fecal pH (P ≤ 0.05). Regardless of hay type, total VFA concentrations were greater (P ≤ 0.05) in the cecum than in feces, and alfalfa resulted in greater (P ≤ 0.05) VFA concentrations than brome in both sampling locations. Alpha diversity was greater (P ≤ 0.05) in fecal compared with cecal samples. Microbial community structure within each sampling location and hay type differed from one another (P ≤ 0.05). Bacteroidetes were greater (P ≤ 0.05) in the cecum compared with the rectum, regardless of hay type. Firmicutes and Firmicutes:Bacteroidetes were greater (P ≤ 0.05) in the feces compared with cecal samples of alfalfa-fed horses. In all, fermentation parameters and bacterial abundances were impacted by hay type and sampling location in the hindgut.

Immunohistochemical study of morphology and distribution of CD163+ve macrophages in the normal adult equine gastrointestinal tract

Intestinal macrophages are the largest group of mononuclear phagocytes in the body and play a role in intestinal innate immunity, neuroimmune interactions and maintaining intestinal homeostasis. Conversely, they also are implicated in numerous pathologies of the gastrointestinal tract, such as postoperative ileus and inflammatory bowel disease. As a result, macrophages could be potential therapeutic targets. To date, there are limited studies on the morphology and distribution of macrophages in the equine gastrointestinal tract (GIT). The aim of this study was to identify the location and abundance of resident macrophages in the equine GIT using CD163 as an immunohistochemical marker. Tissue samples were obtained post-mortem from 14 sites along the gastrointestinal tracts of 10 horses free from gastrointestinal disease; sample sites extended from the stomach to the small colon. CD163+ve cells were present in all regions of the equine GIT from stomach to small colon. CD163+ve cells were also identified in all tissue layers of the intestinal wall, namely, mucosa, submucosa, muscularis externa (ME), myenteric plexus and serosa. Consistent with a proposed function in regulation of intestinal motility, CD163+ve cells were regularly distributed within the ME, with accumulations closely associated with the myenteric plexus and effector cells such as neurons and the interstitial cells of Cajal (ICC).

A Pilot Study Exploring the Relationship Between Digesta Retention Time in the Equine Gastrointestinal Tract and Compartment Models

Digesta retention time within specific segments of the equine gastrointestinal tract (GIT) may be more relevant to scientific inquiries than total tract mean retention time (TTMRT); however, measuring retention time in individual segments requires access to the digestive tract. The objective of this study was to compare prececal, cecal, and colonic mean retention time (MRT) with model-derived compartment MRT. A cecally fistulated gelding was fed indigestible particulate and liquid markers to determine TTMRT and dosed with different pairs of particulate and liquid markers into the cecum (hindgut MRT) and into the right ventral colon through the cecocolic orifice (colon MRT). Fecal marker concentrations were fit to stochastic and mechanistic models using nonlinear least squares methods (MATLAB). Total tract MRT and MRT for each GIT segment were compared with model-derived compartment MRT using paired t-test to determine differences and two one-sided tests to determine equivalence. All models resulted in parameter estimates and an acceptable fit to fecal marker excretion curves, but some parameter estimates did not differ from zero (95% CI included 0). Model-derived TTMRT were equivalent (P < .05) to arithmetically calculated MRT. Most GIT segment MRT differed (P < .05) from model-derived compartment MRT. Differences ranged from −26.1 hours to 25.8 hours. In these exploratory data, model derived compartment retention times failed to pair with MRT in different GIT segments. Significant methodological and analytical challenges remain to describe retention time in individual segments of the equine GIT.

Modification of the equine gastrointestinal microbiota by Jerusalem artichoke meal supplementation.

The objective of this study was to investigate the impact of natural prebiotic active compounds on the microbial composition in different regions of the equine gastrointestinal tract. Twelve adult horses (body weight [bwt] 534 ± 64.5 kg; age 14 ± 7.5 years) were randomly divided into two feeding groups. Six horses received a basal diet consisting of 1.5 kg hay/100 kg bwt x d-1 and oat grains equal to 1.19 g starch/kg bwt x d-1, supplemented with Jerusalem artichoke meal providing prebiotic fructooligosaccharides + inulin in a quantity of 0.15 g/kg bwt x d-1. The remaining horses received a placebo added to the basal diet. The horses were fed for 21 d and euthanized at the end of the feeding period. Digesta samples from different parts of the gastrointestinal tract were taken, DNA extracted and the V1-V2 region of the 16S rRNA gene amplified. Supplementation with the prebiotic increased the relative abundance of Lactobacillus (P < 0.05), with a concurrent reduction of the relative abundance of Streptococcus mainly in the stomach (P < 0.05). In the hindgut, the supplemental prebiotic also increased the relative abundance of Lactobacillus but further reduced the relative abundance of fibrolytic bacteria, specifically the unclassified members of the families Lachnospiraceae (P < 0.05) and Ruminococcaceae. The relative abundance of the genus Ruminococcus increased solely in the caecum and colon transversum. Overall, the addition of the prebiotic significantly increased the diversity in nearly all parts of the gastrointestinal tract (P < 0.05). The feeding of this natural prebiotic compound to horses had an impact on the microbial community in the entire gastrointestinal tract. Furthermore, the effect on the bacterial community in the foregut (especially the stomach) was more pronounced in comparison to the effect in the hindgut. Therefore, the impact on stomach health should be carefully considered.

The impact of nonsteroidal anti-inflammatory drugs on the equine gastric microbiome

Digesta retention time within specific segments of the equine gastrointestinal tract (GIT) may be more relevant to scientific inquiries than total tract mean retention time (TTMRT); however, measuring retention time in individual segments requires access to the digestive tract. The objective of this study was to compare prececal, cecal, and colonic mean retention time (MRT) with model-derived compartment MRT. A cecally fistulated gelding was fed indigestible particulate and liquid markers to determine TTMRT and dosed with different pairs of particulate and liquid markers into the cecum (hindgut MRT) and into the right ventral colon through the cecocolic orifice (colon MRT). Fecal marker concentrations were fit to stochastic and mechanistic models using nonlinear least squares methods (MATLAB). Total tract MRT and MRT for each GIT segment were compared with model-derived compartment MRT using paired t-test to determine differences and two one-sided tests to determine equivalence. All models resulted in parameter estimates and an acceptable fit to fecal marker excretion curves, but some parameter estimates did not differ from zero (95% CI included 0). Model-derived TTMRT were equivalent (P < .05) to arithmetically calculated MRT. Most GIT segment MRT differed (P < .05) from model-derived compartment MRT. Differences ranged from −26.1 hours to 25.8 hours. In these exploratory data, model derived compartment retention times failed to pair with MRT in different GIT segments. Significant methodological and analytical challenges remain to describe retention time in individual segments of the equine GIT.

PSI-16 Exploring the relationship between digesta retention time in the equine gastrointestinal tract and compartment models.

PSI-16 Exploring the relationship between digesta retention time in the equine gastrointestinal tract and compartment models.

Efficacy of faecal microbiota transplantation for treating acute colitis in horses undergoing colic surgery

ABSTRACT: The report describes the outcome of four horses treated with homologous faecal microbiota transplantation (FMT) for acute colitis. The horses developed diarrhoea and fever a few days after a laparotomy to treat gastrointestinal disease. Medical records were reviewed to identify the horses as well as to describe the primary intestinal disease, clinical findings, surgical intervention, FMT protocol, outcome and follow-up of each case. The principle of the efficacy of FMT is that restoration of a balanced nonpathogenic bacterial population may be the primary defence mechanism against colonization of pathogenic bacteria in the equine gastrointestinal tract. The FMT did not produce adverse reactions and was demonstrated to rapidly control diarrhoea and fever in all cases. A complete resolution of clinical sings was observed within 24 hours when horses were given a single FMT. Further clinical studies are necessary to determine the optimal preparation and to reinforce the efficacy of FMT for treating acute colitis following colic surgery. The technique has the potential to be an inexpensive, safe and highly efficient tool for the prevention and treatment of infectious gastrointestinal diseases in horses, preventing antimicrobial resistance.

Substraatgebruik bij paarden tijdens inspanning - een vergelijking tussen de ‘gevaste’ en postprandiale status

Sporten in uitgevaste toestand heeft positieve effecten op het prestatievermogen van humane atleten. Bij paarden gaat trainen in gevaste toestand gepaard met een toegenomen mobilisatie van vrije vetzuren als energiebron. Er wordt verondersteld dat de hogere beschikbaarheid van vet als energiebron leidt tot een minder snelle depletie van spierglycogeen en een trager optreden van spierverzuring. Dit draagt in belangrijke mate bij tot het minder snel optreden van spiervermoeidheid. Omgekeerd zorgt de opname van een graanmaaltijd voor een uitgesproken plasma-insulinepiek en de onderdrukking van lipolyse. Gezien ruwvoer, de hoofdcomponent van het dieet van het paard, een lange passagetijd heeft doorheen de dikke darm, wordt een volledig uitgevaste status bij het paard normaal niet bereikt; dit in tegenstelling tot wat het geval is bij de mens. Het voeren van ruwvoer induceert echter geen uitgesproken plasma-insulinepiek en inhibeert daardoor geen lipolyse. Bovendien zorgt de darmflora in de dikke darm, waar het ruwvoer gefermenteerd wordt, voor een buffer van water en elektrolyten, alsook voor een continue bron van propionzuur. Dit propionzuur wordt verwerkt in de lever, waar het een precursor is voor de gluconeogenese. In tegenstelling tot wat bekend is bij menselijke atleten is er bij paarden nog heel wat te ontdekken wat betreft optimale diëtaire interventies voorafgaand aan competitie enerzijds en training anderzijds. Welke aanpak er ook gekozen wordt, ruwvoer van hoge kwaliteit hoort het sleutelingrediënt te zijn van elk paardendieet. De meeste paarden presteren even goed tot zelfs beter als ze op een dieet staan met een lager suikergehalte (dus minder of geen krachtvoer), op voorwaarde dat hoog kwalitatief ruwvoer wordt aangeboden (gras, voordroog of hooi) in combinatie met een vitaminen/ mineralensupplement. Andere alternatieven om niet-structurele koolhydraten te verlagen in het dieet van een paard met een hoge energiebehoefte is het gebruik van bijvoorbeeld vezelrijke krachtvoeders of gepilleteerde ruwvoerderbronnen, zoals luzernekorrels. Tot slot heeft het frequent voederen van meerdere kleine maaltijden per dag de voorkeur boven het voederen van twee “grote” maaltijden per dag.

Fermentation Characteristics along the Gastrointestinal Tract after Feeding of Jerusalem Artichoke Meal to Adult Healthy Warmblood Horses

Objective: Prebiotics are used to support the gastrointestinal health via stimulating particular beneficial parts of the autochthonous microflora and enhancing their metabolism.Horses often suffer from gastrointestinal disturbances after feed changes or behavioral stress in response to transport. Therefore, the supplementation with prebiotic compounds might reduce the risk for intestinal dysregulation. The aim of this study was to investigate the influence of supplementation with Jerusalem artichoke meal (JAM) in a recommended prebiotic dosage on fermentation characteristics in the equine gastrointestinal tract. Methods: Twelve adult healthy horses received crushed oat grains (1.2 g starch/kg BW x d-1) and meadow hay (as fed basis; 1.5 kg/100 kg BW x d-1). Additionally, they were fed either an apparently prebiotic quantity of fructooligosaccharides (FOS) and inulin (0.2 g/kg BW x d-1) via Jerusalem artichoke meal (JAM) or an equal amount of maize cob meal without grains as control (CON) over 3 weeks. On d21, horses were euthanized, gastrointestinal contents were removed from 7 different regions of the gastrointestinal tract, the dry matter (DM) content, pH value and concentrations of short chain fatty acids (SCFA), L- and D-lactate and ammonia were measured. Results: JAM did not had a significant (P 0.05), lactate (both isomers, P > 0.05) and ammonia (P 0.05) and ammonia (P > 0.05) but lower L-lactate (P > 0.05) concentrations compared to control.

Adhesion of Lactobacillus reuteri strain Lr1 to equine epithelial cells and competitive exclusion of Clostridium difficile from the gastro-intestinal tract of horses

Lactobacillus reuteri Lr1, isolated from healthy horses, remained viable after 2 h at pH 2.0 and in the presence of 1.5 % (w/v) bile. Strain Lr1 survived passage through the equine gastro-intestinal tract (GIT). However, no viable cells of L. reuteri Lr1 were detected on the third day after administration, suggesting that the strain did not colonise the GIT for longer than two days. Strain Lr1 adhered to non-viable, but not to viable, buccal epithelial cells in vitro. Adherence of strain Lr1 to buccal epithelial cells increased 25 % after treatment of the bacterial cells with pepsin. Treatment with pronase prevented the adhesion to epithelial cells. This suggested that specific proteins on the cell surface of L. reuteri Lr1 are involved in adhesion to epithelial cells. Strain Lr1 aggregated with Clostridium difficile C6, isolated from the GIT of a horse that died from severe colic. Adherence of C. difficile C6 to epithelial cells declined from 60 % to 3 % when challenged with L. reuteri Lr1 and the number of viable clostridia decreased tenfold during dosage. Red blood cell, haemoglobin and haemocrit levels were significantly (P ≤ 0.05) lower after dosage with L. reuteri Lr1. Cholesterol and glucose levels were mildly elevated for one day during dosage, but decreased significantly thereafter to levels similar than before dosage. Genes encoding adhesion to collagen, production of aggregation substances, cytolysin and β hemolysin III, resistance to vancomycin A, B and C, and gelatinase activity were not detected, suggesting that L. reuteri Lr1 is a potential probiotic that may be used to control C. difficile cell numbers in the GIT.